Apparatus for producing expanded food stuffs by gaseous conveying heating

ABSTRACT

A method of continuously producing an expanded food stuff, which comprises entraining a material food stuff in a pressurized heated gas stream in a suspended condition, thereby heating and conveying said material, and then discharging the heated material into a gas atmosphere at a lower pressure, whereby said material is expanded. An apparatus for practicing the above-described method, which comprises a conduit for flowing a pressurized heated gas therethrough, means for introducing a material food stuff into the stream of said gas in a suspended condition to be entrained therein, means for collecting the heated material and means for discharging the heated material abruptly into a gas atmosphere at a lower pressure thereby to expand said material.

0 United States Patent [151 3,661,07 1 Toei et al. 51 May 9, 1972APPARATUS FOR PRODUCING [56] References Cited EXPANDED FOOD STUFFS BYUNITED STATES PATENTS GASEOUS CONVEYING HEATING 3,094,059 6/1963 Graham..99/238 [72] Inventors: Ryozo Toei, Kyoto; Tatsuo Aonuma, 3,128,6904/1964 3 Kashiwa shi; Hiroham watanabe; 3,202,084 8/ 1965 Hale "99/238Ifgr both of Neda-Sh! of Primary Examiner-Robert W. Jenkins pAttorney-Cushman, Darby and Cushman [73] Assignee: Kikkoman Shoyu Co.,Ltd., Noda-shi,

Japan [57] ABSTRACT [22] Filed: June 13, 1969 A method of continuouslyproducing an expanded food stuff,

which comprises entraining a material food stuff in a pres- U PP 333,043surized heated gas stream in a suspended condition, thereby heating andconveying said material, and then discharging the heated material into agas atmosphere at a lower pressure, [30] Fore'gn Apphcauon Pnomy Damwhereby said material is expanded.

Oct. 1, 1968 Japan ..43/70808 An apparatus for practicing the abovedescribed method which comprises a conduit for flowing a pressurizedheated [52] US. Cl. ..99/238 R, 99/81 gas therethrough, means forintroducing a material food stuff [51] Int. Cl. ..A23l l/ 18 into thestream of said gas in a suspended condition to be en- [58] Field ofSearch ..99/238, 238.1, 238.5, 238.6, tra ned therein. means forcollecting the heated material and 99 237 8 92 means for discharging theheated material abruptly into a gas atmosphere at a lower pressurethereby to expand said materia1.

2 Claims, 2 Drawing Figures APPARATUS FOR PRODUCING EXPANDED FOOD STUFFSBY GASEOUS CONVEYING HEATING The present invention relates to a methodand apparatus for continuously uniformly expanding materials (e.g.polished rice, glutinous rice, etc.) which are readily gelatinized byheat the, therefore, tend to adhere to and harden on the wall of aheating equipment in which they are heated or tend to form anagglomerate with the particles thereof bonded with each other, materials(e.g. vegetables, fruits, fish and shellfish) which are sensitive toheat and materials of uneven grain size (wide grain size distribution)in particular, not speaking of the ordinary granular or granular foodstuff materials.

The primary object of the present invention is to heat theabove-mentioned materials of food stuffs uniformly and thereby expandthe same efficiently in a short period of time.

The method of producing an expanded food stuff according to the presentinvention comprises passing a pressurizing and heating gas, e.g. apressurized superheated steam, at a pressure of 3 l5 kg/cm G and atemperature of 100 300 C. through a heating conduit, mixing a materialwith said gas by continuously introducing said material into the gasstream, whereby the material is heated in a very short period of time(within seconds) while being entrained in said gas stream, thereaftercollecting the material by a cyclone or the like and discharging thepressurized and heated material continuously abruptly into a gasatmosphere maintained at a lower pressure thereby to expand saidmaterial.

In the process of producing an expanded food stuff heretofore, theso-called indirect-heating method has been employed for heating thematerial food stuff, in which the material is heated by charging it in aclosed cylindrical pressure container or the so-called puffing gun whichis heated externally by a gas burner or the like while being rotated.With this method, however, it is impossible to uniformly heat allparticles of the material and the yield of the product is markedlylowered due to scorching or insufficient heating. In addition, since thematerial is in contact with the wall and also each other, the particlesadhere to the wall of the container or to each other and harden in thatstate where the material has a particularly large amount of free wateror the surface starch of the material is readily gelatinized, thusmaking it impossible to obtain a satisfactory result of the treatment.

In another method used for heating a material, the material is placed inthe aforesaid container or a container provided therein with means formechanically stirring or transporting the material and heated therein bymeans of a heating medium, e.g. a pressurized heating gas, blownthereinto. This method is superior to the preceding method in respect ofheat transfer efficiency and thermal efficiency but still inevitablyinvolves the above-mentioned trouble due to contact of the materialparticles with each other.

There has also been proposed a method (U.S. Pat. application Ser. No.537,730, now U.S. Pat. No. 3,456,575) which is the so-called fluidizedbed heating method and in which a material is fed into a closed pressurecontainer to form a fluidized bed on an apertured plate disposed in saidcontainer and heated in the fluidized state with a gaseous heatingmedium blown upwardly through the apertures in said apertured plate.This method is far superior to the preceding two methods in respect ofthermal efficiency and heat transfer efficiency and in that the materialparticles are heated in a dispersed condition, but is not adapted foruse in the expansion of such a material which contains a relativelylarge amount of water providing for ready gelatinization of the starchthereof or which is sensitive to heat and consists of particles ofuneven particle size.

The above-described problems possessed by the conventional methods andapparatus for expanding food stuffs have been solved easily by themethod and apparatus according to the present invention.

Namely, the present invention has the following advantages:

1. Since a gas stream is used as heating medium, the coefficient ofheat-transfer between a material to be heated and the heating medium isextremely large (or the heat-transfer speed is very high) and,therefore, a heat-expansion treatment can be accomplished in avery shortperiod of time. Practically speaking, an expansion treatment of theordinary cereals can be accomplished only within 10 seconds when theyare heated by a heating medium at a pressure of 5 l5 kg/cmG and atemperature of 200 250 C., as contrasted to a retention time of at least1 minute or longer in case of the conventional expanding method andapparatus.

2. Since a material is intensely stirred and dispersed, not mechanicallybut by the eddy flow of a gaseous heating medium, the particles of thematerial are brought into contact with the apparatus wall or with eachother much less frequently during the period in which the materialresides in the apparatus. Therefore, a treatment of even such a materialwhich has been agglomerated and hardened (into blocks) due to the freewater or the surface starch of which is readily gelatinized by heat orwhich has a relatively large amount of free water (eg polished rice,vegetables, fruits, etc.) can be performed with ease.

3. The heating time can be varied freely by changing the flowingvelocity of a gaseous heating medium. With a constant velocity of a gasstream, the transport velocity of a given material is determined by thephysical properties of said material, such as the particle size, watercontent and shape of the material. Namely, even in case of a materialwith a wide particle size distribution, those particles which arerelatively small in diameter and readily heated are entrained in the gasstream at a relatively high speed and heated in a shorter time, whilstthose particles which are relatively large in diameter and take arelatively long time to be heated are entrained in the gas stream at arelatively low speed and heated for a longer time. Thus, all theparticles are heated uniformly and a uniform expanded food stuff can beobtained.

4. Powdery materials can be treated.

5. Since the pressure-receiving member is essentially a single tube, thestructure of said member can be rendered resistive to pressure in asimple manner and further, since the apparatus involves no moving partfor transporting a material, for a heating period, the operation,maintenance and control of the apparatus are simple.

6. Automatic control can be attained simply.

7. It is possible to transport a material over a long distance whileheating the material.

8. Re-heating and re-circulation of a heating medium are possible.

A preferred embodiment of the present invention will be describedhereunder with reference to the drawings, particularly to FIG. 1.

A material which has previously been subjected to a suitablepre-treatment is continuously fed into a material supply hopper l. Thematerial in the supply hopper l is continuously dropped through a chute3 at a predetermined time interval by means of a rotary feeder 2, to beintroduced into solid substance displacing means 5 (of the typedescribed in Japanese Patent application No. 40/71022) having forceddischarge means 4 and located between closed containers maintained atdifferent pressures. in this case, the displacing means 5 and the rotaryfeeder 2 are operatively correlated through a single chain in such amanner that the material is dropped from the rotary feeder when an inletport 6 of the displacing means is located just at the top of saiddisplacing means.

Where use is made of a superheated steam, a high-pressure steamgenerated in a boiler 7 is heated in a superheater 8 and the resultantsuperheated steam leaving the superheater 8 enters a mixer 9 and thenceflows through a heating conduit 10.

On the other hand, the material displaced by the displacing means 5under sealed condition is fed into the mixer 9 against the high pressureof the superheated steam and then entrained in the steam, flowingthrough the heating conduit 10, in a dispersed condition and transportedin said heating conduit while being subjected to a heat treatment. inthis case, the heating time (or retention time) of the material mayoptionally be changed by'changing the length of the conduit or thevelocity of the steam flowing in said conduit. The material heated for apredetermined time in the heating conduit while being entrained in theflow of steam enters a cyclone 11, wherein it is separated from thesteam and then abruptly discharged into an expansion tank 13, maintagiedat the atmospheric pressure, by means of another displacing means 12having the same construction as that of the aforesaid displacing means5, whereby the material is expanded. On the other hand, the superheatedsteam leaving the cyclone 11 from the top thereof is led through apressure regulating valve 14 to another station where it is used as aheat source (for example, for drying the expanded product or forpreheating the material if such be necessary). Alternatively, the usedsuperheated steam is circulated by a compressor (not shown) for reuse.The length of the heating conduit 10 can be determined by the time whichis required for heating the material to a temperature at which thematerial acquires an amount of heat sufficient for expansion, and thevelocity at which the material moves in the conduit along with thesuperheated steam.

The mixer 9, the heating conduit 10 and the cyclone 11 are heated by theexhaust gases of the superheater 8, which gases are circulated through aheating jacket 15 and discharged therefrom through an exhaust port 16under suction.

Referring to FIG. 2 there is shown a mixer 30 by which sticky materials,such as polished rice, are mixed in the superheated steam flow and whichis used in place of the mixer 9 shown in H6. 1. The mixer has a materialinlet port 31, a heating superheated steam inlet port 32 and anothersuperheated steam inlet port 33. Interior of the material inlet port 31is disposed a perforated inner cylinder 35 having a large number ofapertures 34 formed over the entire surface thereof. The superheatedsteam admitted in the mixer through the inlet port 33 fills an annularspace between the inner wall of the material inlet port 31 and the outerwall of the perforated inner cylinder 35, and sucked into the interiorof said perforated inner cylinder through the apertures 34 formedtherein. Therefore, the material interior of the perforated innercylinder 35 is blown radially inwardly of said inner cylinder by thesteam jetting inwardly through the apertures 34 and thereby preventedfrom adhering to the inner surface of said inner cylinder 35.Occasionally, a whole superheated steam required may be introduced intothe mixer through the inlet port 33.

Now, examples of the expanding operation conducted by the presentinventors using the apparatus of this invention will be illustratedhereinafter:

Example 1 Material: polished rice bulk i000 kg/m (with or withoutdensity rice-bran) water 1. 4.5-] 5% content Heating medium: superheatedsteam pressure 6 kg/cm"'G temperature 250C. (at heating conduit inlet)temperature 200C. (at heating conduit outlet) steam m/sec. velocityMaterial treating capacity (on a continuous basis): 1000 kg/hr.Treatment time (retention time): 6 sec. Properties of the product: water8% content bulk 100 kg/m density conversion to a starch 98% Example 2Material: wheat Bulk 780 Kg/m density water l3.5-|4.5% content Heatingmedium: superheated steam pressure 7 kg/cmG temperature 280C. (atheating conduit inlet) temperature 220C. (at heating conduit outlet)steam 20 m/sec. velocity Treating capacity: 1000 kg/hr.

Treatment time: 8 sec.

Properties of product: water 10% content bulk kg/m" density (Expansionratio about 5 times) Conversion to a starch-99 Example 3 Material:defatted soy bean built 450 kg/m density Water 9.540.591

content particle size distribution 4 mesh 68.5 7: or larger 4 8 mesh18.9% 8 32 mesh 12.67: Heating medium: superheated steam pressure 5kg/cm G temperature 250C. (at heating conduit inlet) temperature 220C.(at heating conduit outlet) steam l 8 m/sec. velocity Treating capacity(on a continuous basis): 500 kg/hr. Treatment time: 5 sec. Properties ofproduct: water 4% content (Note: The protein can be completelydenaturated.

What is claimed is:

1. An apparatus for continuously expanding a food stuff comprising, asource of heated and pressurized gas. a conduit connected at one end tosaid source for continuously flowing said heated, pressurized gastherethrough, a mixer in communication with said conduit downstream ofsaid gas source in the direction of gas flow for continuouslyintroducing said food stuff into said heated, pressurized gas, and aseparating means downstream of said conduit in communication therewithfor continuously separating said heated food stuff from said gas andcontinuously collecting said food stuff, and means in communication withsaid separating means for abruptly discharging said collected food stuffinto air at a lower pressure than said gas, the length of said conduitbetween said mixer and said separating means and the flow rate of thegas and food stuff through said length being sufficient so that the foodstuff introduced at said mixer is fully heated and pressurized by saidgas before reaching said separating means.

2. The apparatus of claim 1 further including a means for guiding thegas exiting from said separating means to a place of use for said gas.

1. An apparatus for continuously expanding a food stuff comprising, asource of heated and pressurized gas, a conduit connected at one end tosaid source for continuously flowing said heated, pressurized gastherethrough, a mixer in communication with said conduit downstream ofsaid gas source in the direction of gas flow for continuouslyintroducing said food stuff into said heated, pressurized gas, and aseparating means downstream of said conduit in communication therewithfor continuously separating said heated food stuff from said gas andcontinuously collecting said food stuff, and means in communication withsaid separating means for abruptly discharging said collected food stuffinto air at a lower pressure than said gas, the length of said conduitbetween said mixer and said separating means and the flow rate of thegas and food stuff through said length being sufficient so that the foodstuff introduced at said mixer is fully heated and pressurized by saidgas before reaching said separating means.
 2. The apparatus of claim 1further including a means for guiding the gas exiting from saidseparating means to a place of use for said gas.